OF ROCKETS. 21 7 



I. Talle of the calibre of moulds of a pound weight and 



The use of (his table will be understood mer ly by inspection ; 

 for it is evident that a rocket of 12 ounces ought to be 17 lines in, 

 diameter ; one of 8 ounces, 15 lines ; one of 10 drams, 6| lines ; 

 and so of the rest. 



On the other hand, if the diameter of the rocket be given, it will 

 be easy to find the weight of the ball corresponding to that calibre. 

 For example, if the diameter be 13 lines, it will he immediately 

 seen, by looking for that number in the column of lines, that it cor- 

 responds to a ball of 5 ounces. 



II. Table of the calibre of moulds from 1 to SO pounds ball. 



The use of the second table is as follows : If the weight of the 

 ball be given, which we shall suppose to be 24 pounds, seek for 



